Which WR should I use with R. Williams (Detroit) - Chad Johnson or Mike Furrey (Detroit)?

Roy Williams has been having a great season, so I am definately starting him. I can start 1 more WR and have Chad Johnson againts a tough San Diego DST and we all know CJ has not had a great year. Mike Furrey has been a surprise in Detroit playing with R. Williams and Kitna and they play San Fran who has been given up a lot of yards and points. Im hesitant to play CJ, but dont want to bench him the week he puts up big points, but Furrey and Detroit may put up a bunch of pts vs SF. I also have Terry Glenn but with possible injury and with TO getting most the looks, I decided not to play him. Who would you use and why? Thanks